1. Field of the Invention
The present invention relates to a scanning method and apparatus, and more specifically, to a scanning method and apparatus by an STA.
2. Related Art
Recent wireless LAN technologies are evolving largely in three ways. Efforts to further increase transmission speed include IEEE (Institute of Electrical and Electronic Engineers) 802.11ac and IEEE 802.11ad as extensions to the existing WLAN evolution. IEEE802.11ad is a wireless LAN technique that employs a 60GH band. Further, broad band wireless LAN utilizing a frequency band of less than 1 GHz is nowadays on the rise to enable transmission in a broader area than by the existing WLAN and such WLAN technologies include IEEE 802.11af utilizing a TVWS (TV White Space) band and IEEE 802.11ah utilizing a 900 MHz band. These standards primarily target expansion of extended range Wi-Fi services as well as smart grid and wide-area sensor networks. Further, the conventional WLAN MAC (Medium Access Control) techniques suffer from the problem that the initial link setup time is significantly increased in some cases. Standardization of IEEE 802.11ai is actively going on to address such issue to thus enable quick access from an STA to an AP.
IEEE 802.11ai is oriented towards the MAC technology that copes with quick authentication procedures for significantly saving initial setup and association time of wireless LAN, and its standardization activities were started with a regular task group on January, 2011. In order to enable a quick access procedure, the IEEE 802.11ai task group is discussing the simplification of the procedures in AC discovery, network discovery, TSF (Time Synchronization Function) synchronization, authentication & association, and process merging with higher layers. Among others, the ideas such as procedure merging utilizing piggyback of DHCP (Dynamic Host Configuration Protocol), optimization of the full EAP (Extensible Authentication Protocol) using concurrent IP, and efficient selective AP (Access Point) scanning are actively under discussion.